Questions tagged [rf]
Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.
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Which matrix index should be used when Y (admittance) is shown to compose a circuit segment mapped to an ABCD matrix? Y21? Other?
I would like to cascade a serial capacitor with a shunt inductor to form an L-match network by multipling two ABCD parameters and convert the result to S-parameters that represent the composite ...
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How do the 5 elementary two-port networks map to unbalanced networks with a common ground?
Background (questions below)
I've been trying to understand how to use S/Y/Z/A-parameter matrixes to create circuits mathematically with 2-port components in series, parallel, and ground-shunt. For ...
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What does \$\beta\$ represent with respect to the length of a transmission line?
The picture below shows the ABCD parameters for a transmission line of length \$l\$ from this video.
Question: What does \$\beta\$ represent?
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Transmit a RF signal without using a microcontroller [closed]
I am looking to to build a game that utilizes two wireless controllers, each with 4 buttons. Each controller will have a RF Transmitter, Transmitting a different signal for each button to a master ...
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Proper PCB layout for GNSS ceramic patch antenna
I am designing a PCB that will require a GNSS antenna. The antenna will feed directly into a GNSS module located on the same board. It seems a popular antenna choice for this is a ceramic patch ...
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Why 7 dB power increase after combining identical strength signals?
I have signals from two transmitters that are combined via a power combiner (link).
Both signals are at 7 dBm when fed into the combiner on their own. When combining both, the meter either reads 7 dBm ...
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Are T-parameters the same thing as ABCD parameters?
S-parameters can be converted to either T-parameters or ABCD-parameters, and both are considered a "transfer matrix". The conversion from S-parameters to T- or ABCD-parameters are defined ...
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Why does this oscillator circuit work well in the simulator, but not in the real implementation?
I want to build a 10MHz sine wave oscillator using a simple BC546 BJT.
This is my schematic and its Multisim simulation:
You can see I am getting around 10.5MHz quite well. When I build this circuit
...
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RF channel noise interference calculation
I am trying to calculate how far a co-channel or noise source has to be from the primary channel, in this case a WiFi channel, for it not to interfere with the link performance.
This question takes ...
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Can admittance (Y) be used to calculate reactance when L and C values are calculated from the Y12 and Y11 parameters like normal as X=XL-XC?
My original question sought to understand the relationship between S-parameters and reactance. In the process of trying to figure that out, this second question arose. The actual question is at the ...
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Determine inductance for lossless microstrip transmission line
Given the following parameters:
Lossless microstrip transmission line of 50 Ω
Capacitance from stripline to ground of 35 pF/m
How can I determine the inductance of the line?
This is a revision ...
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Anticollision system and personel real time tracking system interfering
We are having some problems with either radio frequency interference or EMC/I interference.
There are 2 different units. The one is an anti-collision detection system. The other unit is a real time ...
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Ebyte E32 RF Module Configuration Problem
I designed a PCB with STM32G474RET6. I used Ebyte E32-433T30S module. I search on web and read datasheet. So, I got some info;
This Ebyte module need to be configuration before transmitting/receiving....
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How are S-Parameters and Reactance related, can one be calculated from the other?
I know that, for example, \$X_L=2\pi f L\$ will calculate reactance of an ideal inductor, but can this be calculated for a real component model? Given the S-Parameter values at some frequency from an ...
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How to properly handle mixed RF/digital design in HFSS 3Dlayout
I have a big design imported from Altium into HFSS 3DLayout with several RFIC that I want to simulate. RF and Digital (SPI) nets are included in this design.
I'm interested mainly in the RF side of ...
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Power (dBm) of a non return to zero modulated signal
How to calculate the power (dBm) of this signal which is fed into a receiver with an input impedance of 50 ohms?
The power in dBm formula is 10log(Vrms^2/R)/1mW and R equals 50 ohms. In this case how ...
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With given impedance matching network, how to find the possible matchable load impedance range
I have some questions regarding this schematic using Keysight ADS here. The matching network is intended to function at 13.56MHz. The shunt capacitor has a range of 150-1500pF capacitance and the ...
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How is this possible: Crystal filters for FM signals?
I am trying to make my own superhet reciever. I have achieved downconversion and I am trying to build a crystal filter that will only allow the crystal's resonant frequency through. In doing so, I had ...
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Antenna port S11(dB) > 0
I'm simulating a microstrip patch antenna in microwave office at 35 GHz.
When plotting the S11 in dB of the antenna port I get values greater than zero at frequencies below 28 GHz. How is this ...
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What is the appropriate name for a parabolic antenna with a "center mounted feed"?
How would a parabolic antenna with a "center mounted feed" be called? Below are some images which illustrate the type of parabolic antenna I'm referring to.
According to wikipedia these are ...
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Unable to interface XBEE with m3pi
I have a m3 pi pololu bot (lpc1768 controller) with a mbed slot. I want to send data from a XBEE S1 connected to my PC to the bot (through another XBEE mounted on it).
To achieve this, I've a python ...
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Method for building a test fixture for the 4294A impedance analyzer?
I have an Agilent 4294A, a 40Hz-110MHz impedance analyzer, but no test fixtures to use. Unfortunately the official test fixtures are out of my price range so I need to build some. After reading ...
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Analog television: What is the difference between the first IF and second (demodulated) IF?
I am trying to understand what kind of changes occur to a signal in the chips which sit between the tuner and, for example the FM audio demodulator.
Take the attached example - the TDA2546A. It takes ...
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Frequency Counter Input Impedance
I have been looking at RF frequency counters and noticed that they all have one port that says up to 50 MHz with an input impedance of 1 megaohm. However the +50 MHz input says 50 Ohm impedance.
If ...
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Power combiner for I-Q signals in a transmitter
I have a transmitter project to implement. Part of the project is to combine an in-phase and an out of phase (90 degree difference) signal with a center frequency at 3.5GHz. I figured I could ...
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Simple Diode Mixer Help
Edit:
Thank you for your input @Kevin White, much better results with 100 ohm injection resistors, a 1K resistor for a DC pathway and a 1K bias resistor from Anode to +5V.
I am an RF enthusiast that ...
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Can I solder a wire antenna to the exposed PCB antenna of a BBC Micro Bit to boost its bluetooth signal?
Can I solder a wire antenna to the exposed PCB antenna of a BBC Micro Bit to boost its Bluetooth signal for both transmitting and receiving data?
Can I solder this type of 2.4G antenna to boost the ...
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Achieving good S22 for RF Power Amplifier with minimum power loss
I understand that achieving a S22 can reduce the maximum power and efficiency that can be achieved in a Power Amplifier. Is there any systematic approach to achieve <-10dB S22 while minimizing the ...
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The problem with sensitivity time controlled (STC) based on pin diode
I'm using sensitivity time controlled (STC) pin diodes of PN:MPP 4201A-206 for our applications. Our operating frequency from 1300 MHz to 1400 MHz.
See the schematic diagram below. As device ...
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What is the link between conjugate matching efficiency and amplifier efficiency?
In the design of a class AB amplifier, there is part of the understanding that I miss. It is well-known that the maximum power transfer is achieved when the load impedance is the complex conjugate of ...
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I want to Implement this active inductor design in my circuit
I'm trying to use the active inductor in here instead of the inductor in my class e power amplifier, however I'm having difficulties in getting the required values for the parameters in here
Cds, Cgs, ...
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Output reflection coefficient of a power amplifier
I'm struggling to understand the implication of a poor large signal reflection coefficient at the output of a power amplifier.
I designed a power amplifier and checked the large signal S22 (for the ...
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Motor driver blanks out AM/FM radio reception
Story
I do many restorations of 'boomboxes' (70s/80s/90s) especially the decks inside these units. Next to the common problems with belts, gears, pinch rollers, rubber rings etc there is another issue ...
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Noise factor in homemade software-defined GPS receiver
I'm building a homemade software-defined GPS receiver. I'm currently at a point where I can acquire and track strong signals but struggle to even detect weak signals.
I've ruled out problems with my ...
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How to determine the radiation pattern of a receiver antenna
I am designing a receiver antenna for a wireless power transfer application.
The transmitter is a 2m x 2m horn antenna array that transmits a power signal at a frequency of 35 GHz from 100 meters away ...
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433.2Mhz receiver for Arduino
First of all I'm quite new to the subject of electrical engineering (I'm a software engineer) especially to RF! so forgive me if I forgot something to add to this question. I've done the research but ...
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Audio noise when transmitting radio packets using the ESP32
I am building a sort of walkie-talkie using an ESP32 WROOM chip. I use the internal ADC to sample the microphone and the internal DAC to power small headphones. This all works OK, not the highest ...
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How to choose a sweep range for a known and unknown device with a VNA?
I'm trying to determine best practices for using a VNA to measure say, an antenna.
Let's say I have a known antenna with a spec sheet that says it's frequency range is between x and y. Should I set ...
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Costas Loop QPSK/4QAM
I can use a Costas Loop, modified for QPSK/4QAM and recover the frequency and phase successfully when using a pattern of all 1s or all 0s or a pattern that is repetitive for each I and Q data rail (in ...
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Class AB RF Amplifier with only one active device
I'm designing an amplifier for the 420-440MHz band. I'm looking at using the following part from Ampleon: BLP15H9S100. I'm new to doing RF amplifier work and I've been going through the design process ...
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Allow 12v power through when RF transmitter is close
I'm currently working on a project to allow 12v power through when a RF Transmitter is within a 20 foot range and shuts off then the transmitter is out of range, I'm not so concerned about the range ...
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RF high power amp bias scheme
I am using the TGA2237-SM for the TX side in a front end design. I am trying to figure out an analog method for doing the bias up and bias down procedures.
Bias up
Set gate to Vg=-5V
Increase Vg till ...
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Bandpass filter doesn't work when implementing PCB
I have been trying to make a 5th-order Chebyshev filter going from 500 MHz - 570 MHz and a 3rd-order Chebyshev filter going from 500 MHz - 540 MHz. This is my first time making a filter into a PCB.
No ...
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Diode SPICE data accuracy at high frequencies?
I'm trying to do a non-linear harmonic balance simulation on a schottky diode model MACOM MA4E1317 that according to the manufacturer is usable up to 80 GHz. I got the SPICE data and S-Parameter files ...
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Synchronized two frequency source seems to have phase drift
I have two arbitrary waveform generators which are synchronized at the external but shared 10 MHz clock. My research experiment importantly uses phase-sensitive signals.
The problem I observed is that ...
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Antenna feed trace keep it short or long?
I am designing a GPS module but am quite new to RF design. I have seen a number of people say to keep your antenna feed line as short as possible. But in the design guide of the GPS module I am using, ...
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Designing GPS matching network with TESEO and chip antenna
I am new to designing for RF and have a question regarding the design of the matching network for a GPS module I am working on.
The datasheet of the chip antenna ANT161575ST-1202A1 recommends a ...
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Isolating RF Ground is it wise?
I am designing a GPS module and I am planning to isolate the RF GND from the DC power supply GND with an inductor.
I have chosen the Murata LQW18CN4N9D0ZD because the low inductance will have low Ldi/...
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Does an antenna have to be impedance matched to its transmitter circuit or the transmission line from it?
I am still very new to RF and I am trying to understand Impedance matching, so my question could be stupid.
I have already learned the basics of it, I know how to use Smith charts, which components to ...
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How to prototype with sensitive electrical components without a PCB?
Right now I'm trying to get consistent radio operation with an NRF24L01+ and a Teensy 3.6, however in my experience working with radios they have extremely inconsistent connectivity when using ...
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